(1) Field of the Invention
This invention relates to a substrate treating apparatus for performing a series of treatments of substrates such as semiconductor wafers, glass substrates for liquid crystal displays, glass substrates for photomasks, and substrates for optical disks (hereinafter called simply substrates).
(2) Description of the Related Art
Conventionally, such a substrate treating apparatus is used, for example, in a photolithographic process for forming photoresist film on substrates, exposing the substrates having the photoresist film formed thereon, and developing the exposed substrates.
This apparatus will be described with reference to a plan view shown in FIG. 1. This substrate treating apparatus includes an indexer 103 having a cassette table 101 for receiving a plurality of cassettes C each containing a plurality of (e.g. 25) wafers W to be treated, or wafers W having been treated in treating units 104 described hereinafter, and a transport mechanism 108a movable horizontally along the cassettes C for transporting the wafers W between the cassettes C and treating units 104. The apparatus further includes, besides the treating units 104, a main substrate transport path 105 along which the wafers W are transported from one treating unit 104 to another, and an interface 106 for transferring the wafers W between the treating units 104 and an external treating apparatus 107.
The external treating apparatus 107 is an apparatus separate from the substrate treating apparatus, and is detachably attached to the interface 106 of the substrate treating apparatus. Where the substrate treating apparatus is designed for resist application and development as noted above, the external treating apparatus 107 is an exposing apparatus for exposing the wafers W.
The substrate treating apparatus further includes a main transport mechanism 108b movable along the main substrate transport path 105, and a transport mechanism 108c movable along a transport path of the interface 106. In addition, a table 109a is disposed at a connection between the indexer 103 and main substrate transport path 105, and a table 109b at a connection between the main substrate transport path 105 and interface 106.
The above substrate treating apparatus performs substrate treatment through the following procedure. The transport mechanism 108a takes one wafer W out of a cassette C containing wafers W to be treated, and transports this wafer W to the table 109a to pass the wafer W to the main transport mechanism 108b. The main transport mechanism 108b, after receiving the wafer W placed on the table 109a, transports the wafer W into each treating unit 104 for a predetermined treatment (e.g. resist application) in the treating unit 104. Upon completion of each predetermined treatment, the main transport mechanism 108b takes the wafer W out of the treating unit 104, and transports the wafer W into another treating unit 104 for a next treatment (e.g. heat treatment).
The plurality of treating units 104 include those for performing heat treatment (hereinafter called xe2x80x9cheat-treating unitsxe2x80x9d as appropriate). Some heat-treating units 104 perform, for example, heat treatment after resist application for heat-treating the wafers with photoresist film formed thereon, and other heat-treating units 104 perform heat treatment after exposure for heat-treating the wafers having undergone an exposing process to be described hereinafter. Each heat-treating unit 104 has a hot plate for heating wafers W and a cool plate for cooling the wafers W having been heated, the two plates being arranged one above the other, and a local transport mechanism separate from and independent of the main transport mechanism 108b for transporting the wafers W between the hot plate and cool plate.
The local transport mechanism is provided for each heat-treating unit separately from the main transport mechanism 108b for the following reasons. For the two types of heat treatment after resist application and after exposure noted above, the time taken after a fixed time of heating by the hot plate until the cooling treatment by the cool plate is extremely important from the processing point of view. Variations in that time (i.e. cooling starting time after the heating treatment) would cause variations in film thickness after the resist application or variations in line-width uniformity after the development. If, for example, the main transport mechanism 108b transported the wafer W also between the hot plate and cool plate in each heat-treating unit, it would be difficult to cool, immediately after heating, all of the wafers successively loaded for treatment, because of the time taken in transport to other treating units 104 and the time taken in treatment in other treating units 104. This would result in a so-called overbaking or variations in the cooling starting time after the heating treatment. Thus, the independent local transport mechanism is provided separately from the main transport mechanism 108b to ensure a fixed cooling starting time after the heating treatment.
Further, if the same main transport mechanism were used to transfer wafers to and from the hot plate, the main transport mechanism would become heated and inadvertently apply heat to the wafers. This would affect treatment in other treating units 104 such as resist application and development. The independent local transport mechanism is provided to avoid such an inconvenience also.
After the series of pre-exposure treatment is completed, the main transport mechanism 108b transports the wafer W treated in the treating units 104 to the table 109b, and deposits the wafer on the table 109b to pass the wafer W to the transport mechanism 108c. The transport mechanism 108c receives the wafer W placed on the table 109b and transports the wafer W to the external treating apparatus 107. The transport mechanism 108c loads the wafer W into the external treating apparatus 107 and, after a predetermined treatment (e.g. exposure), takes the wafer W out of the external treating apparatus 107 to transport it to the table 109b. Subsequently, the main transport mechanism 108b transports the wafer W to the treating units 104 where a series of post-exposure heating and cooling treatment and development is performed. The wafer W having gone through all the treatment is loaded by the transport mechanism 108a into a predetermined cassette C. The cassette C is transported away from the cassette table 101 to complete a series of substrate treatment.
The conventional apparatus having such a construction has the following drawback.
The conventional substrate treating apparatus has the local transport mechanism in each heat-treating unit for transporting the wafer W between the hot plate and cool plate to secure a fixed cooling starting time after heating treatment as noted above. In this way, an effort is made for improvement in substrate treating precision. However, variations still occur in substrate treating precision; substrates cannot be treated with high precision.
This invention has been having regard to the state of the art noted above, and its object is to provide a substrate treating apparatus for treating substrates with high precision.
To solve the problem noted above, Inventor has made intensive research and attained the following findings. In the conventional substrate treating apparatus, the local transport mechanism of the heat-treating unit is provided for transporting wafers W between the hot plate and cool plate. The local transport mechanism accesses the hot plate or cool plate in time of wafer transport, and stands by outside the hot plate and cool plate at other times. That is, the local transport mechanism of the heat-treating unit has a standby position set outside the hot plate and cool plate, and stands by in the environment outside the heat-treating unit after transporting a wafer to the hot plate or cool plate. Thus, not only is the local transport mechanism easily affected by the influence (e.g. thermal influence) of the environment outside the heat-treating unit, but, conversely, the local transport mechanism exerts an influence (e.g. thermal influence) on the environment outside the heat-treating unit. It has been found that the influence on the local transport mechanism of the environment outside the heat-treating unit and vice versa are in a causal relationship with variations in substrate treating precision and a lowering of treating precision of the substrate treating apparatus.
Based on the above findings, this invention provides a substrate treating apparatus for performing a series of treatments on a substrate, comprising a heat-treating unit for heat-treating the substrate, and a main transport device for transferring the substrate between the heat-treating unit and a different unit, the heat-treating unit including a plurality of substrate treating sections arranged vertically, and a local transport device provided separately from the main transport device for transferring the substrate between the substrate treating sections, one of the substrate treating sections providing a standby position for the local transport device.
According to the above apparatus, the local transport device, when on standby, is placed in the standby position inside one of the substrate treating sections of the heat-treating unit. Consequently, the local transport device is less influenced by the environment outside the heat-treating unit than where the local transport device is kept on standby outside the heat-treating unit. The local transport device on standby influences the environment outside the heat-treating unit to a reduced degree. Variations in substrate treating precision due to such adverse influences may be reduced to perform substrate treatment with high precision. Further, temperature control of the local transport device may be effected easily. The local transport device capable of transferring the substrate between the plurality of substrate treating sections in the heat-treating unit lightens the burden on the main transport device.
Preferably, the substrate treating sections include a substrate heating section for heating the substrate, and one of a substrate cooling section for cooling the substrate and a substrate standby section for keeping the substrate on standby, the standby position being set inside one of the substrate cooling section and the substrate standby section. Thus, the local transport device, when on standby, is placed in the standby position inside the substrate cooling section or substrate standby section. The local transport device on standby is less influenced by the environment outside the heat-treating unit, and influences the environment outside the heat-treating unit to a reduced degree. Variations in substrate treating precision due to such adverse influences may be reduced to perform substrate treatment with high precision. Where the standby position is set inside the substrate cooling section, the local transport device on standby may be cooled.
Preferably, the local transport device includes a substrate cooling device for cooling the substrate held by the local transport device. This local transport device not only transports the substrate, but can start cooling the substrate the moment it holds the substrate.
Preferably, at least one of the substrate treating sections has, formed separately from each other, a local transport opening for access by the local transport device, and a main transport opening for access by the main transport device. This construction reduces the chance of interference between the local transport device and main transport device.
Preferably, one of the substrate cooling section and the substrate standby section includes a cooling device for cooling the local transport device on standby. The cooling device may cool the local transport device on standby inside the substrate cooling section or substrate standby section.
Preferably, the substrate treating sections include at least two substrate heating sections for heating the substrate, one of the substrate heating sections providing the standby position for the local transport device. With this construction, the local transport device on standby is placed in the standby position inside one of the substrate heating sections. Thus, the local transport device on standby is less influenced by the environment outside the heat-treating unit, and influences the environment outside the heat-treating unit to a reduced degree. Further, the local transport device on standby may be heated.
Alternatively, the substrate treating sections may include at least two substrate cooling sections for cooling the substrate, one of the substrate cooling sections providing the standby position for the local transport device. With this construction, the local transport device on standby is placed in the standby position inside one of the substrate cooling sections. Thus, the local transport device on standby is less influenced by the environment outside the heat-treating unit, and influences the environment outside the heat-treating unit to a reduced degree. Further, the local transport device on standby may be cooled.
This specification discloses also the following substrate treating method, substrate heat-treating apparatus and substrate transporting methods for a substrate treating apparatus:
(1) A substrate treating method for performing a series of treatments on a substrate, comprising:
a main transport step for transporting the substrate with a main transport device between a heat-treating unit for heat-treating the substrate and a different unit;
a local transport step for transporting the substrate with a local transport device between a plurality of substrate treating sections arranged vertically in the heat-treating unit; and
a standby step for placing the local transport device having transported the substrate to a predetermined one of the substrate treating sections in the heat-treating unit, in a standby position set inside a different one of the substrate treating sections.
According to the substrate treating method (1) above, the standby step is executed to place the local transport device having transported the substrate to a substrate treating section, in a standby position set inside a different substrate treating section. Consequently, the local transport device is less influenced by the environment outside the heat-treating unit than where the local transport device is kept on standby outside the heat-treating unit. The local transport device on standby influences the environment outside the heat-treating unit to a reduced degree. Variations in substrate treating precision due to such adverse influences may be reduced to perform substrate treatment with high precision. Further, temperature control of the local transport device may be effected easily. The local transport device capable of transferring the substrate between the plurality of substrate treating sections in the heat-treating unit lightens the burden on the main transport device.
(2) A substrate treating apparatus for performing a series of treatments on a substrate, comprising:
a plurality of substrate treating sections arranged vertically for performing predetermined treatments on the substrate; and
a local transport device provided separately from a main transport device that transfers the substrate between the substrate treating apparatus and a different apparatus, the local transport device transferring the substrate between the substrate treating sections;
one of the substrate treating sections providing a standby position for the local transport device.
According to the substrate treating apparatus (2) above, the local transport device, when on standby, is placed in the standby position inside one of the substrate treating sections of the heat-treating unit. Consequently, the local transport device is less influenced by the environment outside the heat-treating unit than where the local transport device is kept on standby outside the heat-treating unit. The local transport device on standby influences the environment outside the heat-treating unit to a reduced degree. Variations in substrate treating precision due to such adverse influences may be reduced to perform substrate treatment with high precision. Further, temperature control of the local transport device may be effected easily. The local transport device capable of transferring the substrate between the plurality of substrate treating sections in the heat-treating unit lightens the burden on the main transport device.
(3) A substrate transport method for a substrate treating apparatus for performing a series of treatments on a substrate, comprising:
a first main transport step for transporting the substrate with a first main transport device between a substrate treating section for cooling or standby in a heat-treating unit for heat-treating the substrate, and a different unit;
a second main transport step for transporting the substrate with a second main transport device between a substrate heat-treating section different from the substrate treating section for cooling or standby in the heat-treating unit, and another different unit;
a local transport step for transporting the substrate with a single local transport device separate from the first and second main transport devices, between the substrate treating section for cooling or standby and the substrate heat-treating section arranged vertically in the heat-treating unit; and
a standby step for placing the local transport device having transported the substrate to one of the substrate treating section for cooling or standby and the substrate heat-treating section in the heat-treating unit, in a standby position set inside the other of the substrate treating section for cooling or standby and the substrate heat-treating section.
According to the substrate transport method (3) above, the standby step is executed to place the local transport device having transported the substrate to one substrate treating section, in a standby position set inside a different substrate treating section. Consequently, the local transport device is less influenced by the environment outside the heat-treating unit than where the local transport device is kept on standby outside the heat-treating unit. The local transport device on standby influences the environment outside the heat-treating unit to a reduced degree. Variations in substrate treating precision due to such adverse influences may be reduced to perform substrate treatment with high precision. Further, temperature control of the local transport device may be effected easily. The first main transport device accesses only the substrate treating section for cooling or standby, while the second main transport device accesses only the substrate heat-treating section. Thus, a thermal separation is provided between the first main transport device and second main transport device.
(4) A substrate transport method in a substrate treating apparatus for performing a series of treatments on a substrate, comprising:
a main transport step for transporting the substrate with a single main transport device between a particular one of a plurality of substrate treating sections arranged vertically in a heat-treating unit for heat-treating the substrate, and a different unit;
a local transport step for transporting the substrate with a single local transport device separate from the main transport device, between the substrate treating sections in the heat-treating unit; and
a standby step for placing the local transport device having transported the substrate from the particular one of the substrate treating sections to a different one of the substrate treating sections, in a standby position set inside the particular one of the substrate treating sections.
According to the substrate transport method (4) above, the standby step is executed to place the local transport device having transported the substrate to a substrate treating section other than a particular substrate treating section, in a standby position set inside the particular substrate treating section. Consequently, the local transport device is less influenced by the environment outside the heat-treating unit than where the local transport device is kept on standby outside the heat-treating unit. The local transport device on standby influences the environment outside the heat-treating unit to a reduced degree. Variations in substrate treating precision due to such adverse influences may be reduced to perform substrate treatment with high precision. Further, temperature control of the local transport device may be effected easily.